package com.hulk.utils;

import java.math.BigDecimal;

public class LocationUtil {
	/**
	 * 计算地球上任意两点(经纬度)距离
	 * 
	 * @param long1
	 *            第一点经度
	 * @param lat1
	 *            第一点纬度
	 * @param long2
	 *            第二点经度
	 * @param lat2
	 *            第二点纬度
	 * @return 返回距离 单位：米
	 */
	public static double getDistance(double long1, double lat1, double long2, double lat2) {
		double a, b, R;
		R = 6378137; // 地球半径
		lat1 = lat1 * Math.PI / 180.0;
		lat2 = lat2 * Math.PI / 180.0;
		a = lat1 - lat2;
		b = (long1 - long2) * Math.PI / 180.0;
		double d;
		double sa2, sb2;
		sa2 = Math.sin(a / 2.0);
		sb2 = Math.sin(b / 2.0);
		d = 2 * R * Math.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat1) * Math.cos(lat2) * sb2 * sb2));
		return d;
	}
	
	
	/**
	 * 格式化坐标间距离
	 * @param distance
	 * @return
	 */
	public static String showDistance(Double distance){
		   String distanceStr="";
		   if (distance <100.001){
			   distanceStr = "<"+ Math.round(distance) + "m";
		   }else if (distance>100.0001 && distance<1000.0001){
			   distanceStr =  Math.round(distance) + "m";
		   }else{
			    double kmDistance = distance / 1000;
				BigDecimal bd = new BigDecimal(kmDistance);
				kmDistance = bd.setScale(2, BigDecimal.ROUND_HALF_UP)
						.doubleValue();
				distanceStr =  kmDistance + "km";			   
		   }
		   return distanceStr;
	}
}
